To prove two triangles are congruent by the SAS (Side-Angle-Side) Postulate, we need to know that two sides and
the included angle of one triangle are congruent to two sides and the included angle of another triangle. The
information given states that TD = SG
and MD = SL. To use the SAS
Postulate, we need the angle between TD and MD in triangle TMD to be congruent to the angle between SG and SL in triangle SGL. Therefore, the additional information needed is that
LTDM = LSGL.
However, in the image provided,
LTDM is marked as LD and LSGL is
marked as LS. So, the correct statement to prove the two triangles congruent by SAS is LD = LS.
